Melatonin for Sleep Quality
Melatonin reliably shortens the time it takes to fall asleep, but its effect on overall sleep quality and staying asleep through the night is small and inconsistent. It works best as a signal that nudges your body clock toward sleep, not as a true sleeping pill.
Why this grade7-layer evidence engine
This earns a Preliminary (B) grade because several high-quality reviews point the same way, yet the benefit for sleep quality itself is clinically small. A 2022 meta-analysis of 23 trials (PMID 33417003) improved Pittsburgh Sleep Quality Index scores by about 1.2 points versus placebo, but the gain was largest in people with respiratory or metabolic conditions and smallest in those with primary sleep disorders. An older meta-analysis of 1,683 patients (PMID 23691095) cut sleep-onset time by roughly 7 minutes and added only about 8 minutes of total sleep, with a small effect on quality (SMD 0.22).
A 2026 umbrella review (PMID 41014554) found about 81% of pooled analyses favored melatonin, but it was funded by a melatonin manufacturer, so that figure should be read cautiously. The consistent pattern is that the evidence for falling asleep faster is firmer than for sleeping better overall.
Authorities mirror this split. The EU's EFSA endorses only the narrow claim that melatonin shortens sleep-onset latency, while the US FDA does not consider it generally safe in food and the UK NHS keeps it prescription-only. Mayo Clinic, Harvard Health, Cleveland Clinic and the NIH supplement office are uniformly cautious, calling whole-night effects unclear or minimal, though short-term use appears reasonably safe.
Scoring transparency
All scores computed by a 7-layer evidence engine — fully auditable▸View the full decision path (audit trail)
- compute_raw_score — 加權公式: L2×0.30 + L3×0.25 + L5×0.25 + L11×0.10 + L1×0.10 = 0.558
- tier_from_score — 依分數區間映射至 tier letter
- apply_hec_rules — 高品質 SR/MA 顯示 positive (3 篇 > 0 negative)
- tier_strict_requirement_check — Tier 條件達標，未降階
- detect_disputes — 偵測到 0 個 hard + 0 個 soft dispute
- decide_status — 依 tier + dispute 結果決定 status